Mercury vapor lamp manufacture



July 9, 1957 c. MOREHEAD MERCURY VAPOR LAMP MNUF'ACTURE 2 Sheets-'Sheet Jl Filed June l, 1954 l. MMG/19V IN VEN TOR.

July 9, 1957 l QMQREHEAD 2,798,786

MERCURY VAPOR LAMP MANUFACTURE 1 Filed June l, 1954 2 Sheets-Sheet 2 To VMM/M 14a/.VE

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TIPPl/VG FF LL/l MERCURY LAB/lili" MANUFACTURE Chalmers Morehead, Montciair, N.. ll., assigner to Westinghouse Electric Corporation, East Pittsburgh, Ilia., a corporation of Pennsyivania Appiicntion .inne Il, 1954, Serial No. 433,475

#l {CL Siem-22) This invention relates tov mercury vapor lamp manufacture and has particular utility in the manufacture of fluorescent lamps.

In present-day fluorescent lamp manufacture, mercury is admitted to the hot lamp after treating the cathode coils. Part of the mercury is vaporized and the residual gas then in the lamp is forced out through the exhaust tube in advance of the wave of mercury vapor. However, it is customary to continue heating the cathode coils in the hot mercury vapor to provide end arcing and later lamp arcing from electrode to electrode. Any `additional gas or impurities driven olf from the cathode coils or other lamp parts within the envelope during this end arcing and lamp arcing will, by this prior art practice, be trapped by the surrounding mercury vapor and will be retained in the lamp when the argon fill is admitted.

According to the present invention, I propose a remedy for this condition and solution to the vexing problem presented thereby.

More specifically, the invention contemplates removal from the lamp of the impurities `developed during the arcing cycles.

Other objects, advantages and distinguishing characteristics of the invention will appear to persons skilled in the art to which it appertains as the description proceeds, both by direct reference thereto and by implication from the context.

`While the invention may be performed by or with machines of varying construction, for illustrative purposes I have arbitrarily shown a particular lamp-making machine herein, but it is to be understood the invention is not confined to that machine alone. In the accompanying drawings,

Fig. 1 is a sectional elevation of a machine showing one of the lamp-carrying heads at a station at which my invention applies more particularly;

Fig. 2 is a detail of piping connections to the head for evacuating and Igas till purposes; and

Fig. 3 is a somewhat diagrammatic plan of the rotor for showing the sequence of operations in which the present invention is involved.

The general organization of the machine herein arbitrarily shown is much the same as in the prior Campbell Patent No. 2,533,712 of December l2, 1950 assigned to the same assignee as the present invention. It comprises a rotor 11 which is rotatably mounted and driven with step-by-step indexed rotation. Peripherally of the rotor are carried heads 12, of which one is shown in Pig. l, having a rubber exhaust temporary sealing member 14 at its bottom end receiving the exhaust tube 15 of fluorescent lamp or other device 16. Above the head and axially aligned with the tubulation of the lamp is a mercury doser 17 operation of which is with appropriate spring loading or by gravity to closed position, and actuation to open position by a solenoid 18. When the mercury doser is actuated to open position, a measured quantity of mercury ydrops through vertical passageway 19 in the head and into the tubulation 15 and thence to the ttes arent C) lamp. As mercury dosers of this character are well known in the art, further description thereof is deemed unnecessary. In the rotor cycle, prior to the mercury dosing, the lamp is evacuated by way of said tubulation and passageway 19 to which a vacuum line 50 is connected. A rubber tube pinch valve 51 is provided in said Vacuum line in proximity to its connection to the head passage# way i9, so that, as by an automatically operated pinch lever S2, the line may be closed after the evacuating cycle is complete, or at such other interval as found desirable. The close relation of the valve .51 to passage` way 19 is desirable in order that impurities pumped from the lamp will not have opportunity to return thereinto when the valve is closed. The specic machine illustrated provides for forty-eight stations and therefore the rotor will have that many heads around its periphery. There is a vacuum lline from each head, each having a mercury trap 53 and each leading to its respective downe wardly directed port S4 which, at most of the stations, and being in a circular series, registers with corresponding fixed ports 55, in the upper face of a lower fixed valve ring 56 on which the rotor rides. These :fixed po'rts are connected in groups with vacuum manifolds 57 each having a vacuum pump 58.

Fill gas, of which argon is an example, is introduced only at one station, namely the last station before the tabulation is sealed or tippedbff. The rotor has a second circular series of ports S9 therein, one for each head, at a different radial location from the exit of the rotor than the vacuum ports, and the fixed valve ring 56 has a single port 60 at the proper location to supply the head with lill gas at the one station where it is wanted. A pipe line 61 is provided from `each till gas port 59 to the respective head, this line being shown as opening at 62 into the vertical passageway 19 of the head. Said line likewise has a rubber tube pinch valve, and of construction corresponding to the vacuum line pinch Valve, and casing for which is shown at 63, adapted to be closed by an automatically operated pinch lever 64 for most of the cycle of the rotor and opened at the one station mentioned. It will be understood that the machine provides properly constructed mechanism or cams 65 and 66 for swinging the projecting end of the pinch levers 22 and 64 respectively when the valves are to be closed and applying reverse operation when the valves are to be opened. In Fig. l the pinch valve for the Vacuum line is shown open and the pinch lever 64 for the fill gas line is in line closing position.

Approximately the iirst half of the rotary cycle of the rotor is utilized for evacuation and baking of the envelope as usual, and with which this invention has no direct concern. Thereafter a considerable part of the remaining cycle involves cathode treating during which the vacuum lines are open to the pumps and the lamp continuously evacuated at each of the stations. For a machine, such as indicated with forty-eight stations, cathode treating is performed from stations 25 to #itl inclusive, and in this part of the cycle, let us say at station 30, solenoid 1S is energized, for operating mercury doser 1'7 to drop a measured quantity of mercury to and through tubulation 15 into the lamp, thereby supplying a first mercury dosing to the lamp. It will be understood that the envelope is hot when the mercury is introduced thereinto as customary in the art, and therefore the mercury is vaporized in whole or in part and the envelope is thereby llooded with mercury vapor which rises from the bottom toward the top of the envelope where evacuation is taking place. Thus, the gases and impurities in suspension therein are evacuated as the mercury vapor rises, and by the time the indexing brings the lamp, say to station 36, the envelope is filled with mercury vapor. From stations 37 to di), current is applied to the electrodes 76, 7) as usual to effect first end arcing and thereafter lamp arcing, all of the stations from 2S to 4@ being the part of the cycle known as cathode treating. Since the mercury vapor prevails throughout the envelope during the arcing aforementioned, gas and impurities driven from the electrodes 70 or other interior parts of the lamp during that portion of the cycle will be trapped in the mercury vapor, and, according to prior art practice permanently remain in the lamp.

According to the present invention, immediately following the cathode treating cycle, a second dose of mercury is admitted by doser 17 at station 41. The drop of this second dose of mercury naturally falls to the bottom end of the lamp remote from the exhaust tubulation,

and since the lamp is hot, becomes at least in part vaporized and this fresh supply of mercury vapor pushes the tirst and contaminated charge of mercury vapor upward the tubulation. At the stations 4l and 42 where this fresh and final supply of mercury is rising, a hyper-vacuum is applied to the tubulation suicient to evacuate the contaminated first supply of mercury, assisted by the pushing effect of the rising fresh supply, and thus the impurities are likewise withdrawn, mixed with the evacuated first supply of mercury vapor, leaving substantially only the second and pure supply of mercury vapor in the lamp.

At the next following station 43, the vacuum port 54 is closed and the port 59 to the argon fill supply is opened, thereby admitting a requisite supply of argon to the lamp accompanied by a preheating of the tubulation so that the tubulation contracts and then is fully tipped off. Thus the lamp is sealed and contains only the substantially pure mercury Vapor and argon gas, the impurities having been removed with the first supply of mercury vapor. Tests have shown a decided gain in lumens and a reduction in lamp wattage for lamps made in accordance with the above-described method over lamps made with the conventional single dose of mercury following prior art practice. Also, tests have proven that the gaseous products removed from the lamp, exclusive of mercury vapor, by utilization of the evacuation of the rst dose and replacement by the second dose of mercury in accordance with my invention is in the range of three microns for a 40 watt T12 size of fluorescent lamp.

l claim:

1. A method of lamp manufacture comprising a first mercury dosing of the lamp, applying current to the cathode and obtaining end arcing and lamp arcing in presence of mercury vapor of said irst dosing, entrapping impurities in the mercury vapor of the first dosing, and pushing the said vapor and entrapped impurities from the lamp by replacing with Vapor of a second dosing of mercury.

2. A method of lamp manufacture comprising a first mercury dosing of the lamp, applying current to the cathode and obtaining end arcing and lamp arcing in presence of mercury vapor of said first dosing, entrapping impurities in the mercury vapor of the first dosing, and simultaneously applying a second dosing of mercury and evacuation to the lamp so as to obtain combined pushing and evacuation of the vapor of the first dosing and the entrapped impurities therein and replacement thereof -with vapor of said second dosing of mercury.

3. A method of lamp manufacture comprising a first mercury dosing of the lamp, applying current to the cathode and obtaining end arcing and lamp arcing in presence of mercury vapor of said first dosing, entrapping impurities in the mercury vapor of the first dosing, and simultaneously applying a second dosing of mercury and evacuation to the lamp so as to obtain combined pushing and evacuation of the vapor of the first dosing and the entrapped impurities therein and replacement thereof with vapor of said second Closing of mercury and thereafter injecting a fill gas into the lamp to supplement the mercury Vapor, and sealing the lamp.

4. A method of fluorescent lamp manufacture comprising, a first mercury dosing of the lamp While hot before sealing, applying a potential to the cathodes of the lamp to produce end arcing and lamp arcing, entrapping impurities in the mercury vapor of the rst dosing, applying a second dosing of mercury to one end of the envelope of the still-hot lamp, evacuating the envelope from the end opposite to that holding said second mercury dosing so as to obtain combined pushing and evacuation of the vapor of the first mercury `dosing and the entrapped impurities therein and replacement with vapor of said second dosing of mercury, thereafter injecting a iill gas into the lamp to supplement the mercury fill, and sealing the lamp.

References Cited in the file of this patent UNiTED STATES PATENTS 1,874,018 Machlctt Aug. 30, 1932 2,249,672 Spanner luly l5, 1941 2,449,637 Blake et al Sept. 2l, 1948 

1. A METHOD OF LAMP MANUFACTURE COMPRISING A FIRST MERCURY DOSING OF THE LAMP, APPLYING CURRENT TO THE CATHODE AND OBTAINING END ARCING AND LAMP ARCING IN PRESENCE OF MERCURY VAPOR OF SAID FIRST DOSING, ENTRAPPING IMPURITIES IN THE MERCURY VAPOR OF THE FIRST DOSING, AND 